We have no idea if Mihawk went to Wano or not. For someone to claim he didn't go to Wano his headcannon.
Mihawk could have went to Wano looking to fight Oden. Find out he was dead and left because there was no more worthy swordsman alive for him to challenge. Days after Oden was executed the rest of the strong samurai were either killed or imprisoned by Kaido.
A Wano citizen not mentioning Mihawk doesn't mean anything. Why would they talk about Mihawk when they would be more concerned about where to get fresh food and water from and whether they will live through the night. No citizen talks about Kaido vs Moria fight so why would they talk about Mihawk that has no effect on their daily lives. They wouldn't.
If Mihawk was in Wano at some point in the story how do some of you expect a conversation about him to go? I can see it now, two random Wano citizens talking about Kaido and how they hate what he's done to their country. Then one randomly starts talking about how years ago a mysterious swordsman (Mihawk) showed up to fight Oden. After he he found out Oden was dead beat a few weak swordsman and then left upset.